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  • Question
  • The sum of how many terms of the series 6 + 12 + 18 + 24 + ... is 1800?


  • Options
  • A. 16
  • B. 24
  • C. 20
  • D. 18
  • E. 22

  • Correct Answer
  • 24 

    Explanation
    This is an A.P. in which a = 6, d = 6 and S n = 1800

    Then, n [2a + (n - 1)d] = 1800
    2

    ⟹  n [2 x 6 + (n - 1) x 6] = 1800
    2

    ⟹ 3n (n + 1) = 1800

    n(n + 1) = 600

    n2 + n - 600 = 0

    n2 + 25n - 24n - 600 = 0

    n(n + 25) - 24(n + 25) = 0

    ⟹ (n + 25)(n - 24) = 0

    n = 24

    Number of terms = 24.


  • Numbers problems


    Search Results


    • 1. Which of the following numbers will completely divide (461 + 462 + 463 + 464)?

    • Options
    • A. 3
    • B. 10
    • C. 11
    • D. 13
    • Discuss
    • 2. 9548 + 7314 = 8362 + (?)

    • Options
    • A. 8230
    • B. 8410
    • C. 8500
    • D. 8600
    • E. None of these
    • Discuss
    • 3. The smallest prime number is:

    • Options
    • A. 1
    • B. 2
    • C. 3
    • D. 4
    • Discuss
    • 4. If x and y are positive integers such that (3x + 7y) is a multiple of 11, then which of the following will be divisible by 11?

    • Options
    • A. 4x + 6y
    • B. x + y + 4
    • C. 9x + 4y
    • D. 4x - 9y
    • Discuss
    • 5. On dividing 2272 as well as 875 by 3-digit number N, we get the same remainder. The sum of the digits of N is:

    • Options
    • A. 10
    • B. 11
    • C. 12
    • D. 13
    • Discuss
    • 6. 666 / 6 / 3 =?

    • Options
    • A. 37
    • B. 333
    • C. 111
    • D. 84
    • E. None of these
    • Discuss
    • 7. Which one of the following numbers is completely divisible by 99?

    • Options
    • A. 3572404
    • B. 135792
    • C. 913464
    • D. 114345
    • E. None of these
    • Discuss
    • 8. The H.C.F. of 910, 1225, 1835 and 2140 is:

    • Options
    • A. 35
    • B. 2525
    • C. 31400
    • D. 63700
    • Discuss
    • 9. Find the greatest number that will divide 43, 91 and 183 so as to leave the same remainder in each case.

    • Options
    • A. 4
    • B. 7
    • C. 9
    • D. 13
    • Discuss
    • 10. 252 can be expressed as a product of primes as:

    • Options
    • A. 2 x 2 x 3 x 3 x 7
    • B. 2 x 2 x 2 x 3 x 7
    • C. 3 x 3 x 3 x 3 x 7
    • D. 2 x 3 x 3 x 3 x 7
    • Discuss


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